The present invention relates to a semiconductor photodetector whose spectral sensitivity is controlled to the visible light region by a combination of a semiconductor light receiving element having spectral sensitivity from the visible light region to the infrared region and an optical transmitting resin in which micro particles block the infrared region.
As a photodetector, a CdS cell having spectral sensitivity characteristics as shown in FIG. 6 has been widely used. However, since cadmium is high in environmental burdens and falls under a controlled substance by RohS command of EU, cadmium will be prohibited to use within EU from July 2006. As a replacement of cadmium, a photodetector formed from silicon has been used. In order to compose a photodetector with silicon, spectral sensitivity characteristics of silicon (FIG. 7) needs to be coordinated with relative luminous characteristics (FIG. 8) which is sensitivity of human eyes.
In order to achieve this, a filter composed of multilayer film in which an oxide silicon (SiO2) film and a titanium oxide (TiO2) film are alternatively laminated has been provided at a light receiving surface side of a silicon light receiving element to lower spectral sensitivity of the infrared region within the spectral sensitivity of silicon, to thereby approximate to relative luminous characteristics (FIG. 8) in prior art (see, for example Japanese Unexamined Patent Publication No. 15044/1997).
However, formation of the multilayer film in which an oxide silicon (SiO2) film and a titanium oxide (TiO2) film are alternatively laminated is a troublesome task in terms of time and processes, and results in high cost. In other words, the multilayer film is formed by multiple times of vacuum plasma evaporation, and a bonding pad is etched to be open for electrical connection after the formation of the multilayer film. These processes require special techniques in addition to the time consuming processes, thus resulting in high cost.
An object of the present invention is to provide a semiconductor photodetector which can achieve spectral sensitivity characteristics close to relative luminous characteristics at low cost while using a light receiving element of a semiconductor such as silicon.